Microsoft has seen a 300 percent increase in the number of Web sites hosted on its recently launched Windows Server 2003 software in the last three months -- with a considerable amount of the new business representing migrations from Linux, according to a survey published this week.

The figures are a win for Microsoft, which dominates the desktop operating system market but currently rates a distant second to the open-source Apache, often running on Linux, in servers. Open-source software is not controlled by any one organisation, and can often be obtained and maintained far more cheaply than proprietary software.

The number of active Web sites hosted on Server 2003 tripled to 88,400 in the three months since launch, according to Netcraft, which monitors server usage. A significant portion of this growth has been at the expense of the Linux operating system, with 5 percent having migrated from Linux.

"Microsoft will take some considerable encouragement at the number of sites that have switched from Linux," Netcraft said in its report.

Forty-two percent of the sites running on Microsoft's new server are new sites, 43 percent are upgrades from other Windows platforms, mainly Windows 2000, and 1 percent are migrations from operating systems other than Linux or Windows, according to Netcraft.

The company also noted that the number of sites running on the FreeBSD version of Unix have continued to increase -- the only operating system besides Linux and Windows that the survey has found to be on the rise, rather than losing market share, in the server space.

The number of hostnames using FreeBSD is nearing four million, while the number of active sites is nearly two million, Netcraft said. Most of these sites are accounted for by companies with shared hosting systems, including Yahoo, which can operate hundreds of thousands of sites as part of a single system. Yahoo accounts for 159,354 of the FreeBSD sites, with 152,054 from NTT/Verio and 129,378 from Infospace, the survey found.

"Never has an operating system used by so many been administered by so few," Netcraft's report said.

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